Mental Illness/psychosis as possible explanation in mysteries?

I was rereading some information today about a few cases, and got to wondering: how many of these could be attributed to psychosis or mental illness or (as maybe in one case) drug interaction?

This article about psychosis as a side effect of cefuroxime may be widely distributed and read, but I thought it was interesting as it might relate to the case of Lars Mittank. Could it really be that easy?

The next one where I really think that a mental illness or psychosis of some kind was involved is that of Blair Adams, that link to Unsolved Mysteries, or also here on this sub from a while back and elsewhere, I’m sure.

I want to mention something else as related to Adams, and I don’t have any other way to put it except for ‘self-fulfilling prophecy.’ Hear me out.

In the Blair Adams case, or really any like it, how probable/possible is it that someone, for whatever reason (recreational drug use, prescription drug interactions, stress, sleep deprivation, etc.) really begins to believe that someone is after them, gets more and more out of control and runs into trouble (or has an accident) as a result? Someone gets run over by a car, runs into someone who gets tired of their shit because they're not in their right mind, falls off a bridge, whatever. I’m not suggesting those are fitting explanations, specifically, but I feel like if, with those two cases, those people really weren’t being followed, that a run-in with the wrong person, or an accident, as a result of that psychosis/whatever is the only other explanation, but granted would be an enormous fluke. As an extension of that, how likely is it that a similar mental condition/state is an underlying factor in cases where people exhibited no prior history? Maura Murray? Brandon Lawson? Asha Degree?!
I’m not saying I think that’s what happened at all, especially since ‘fugue states’ and retrograde amnesia are fictionalized and portrayed as far more common than they actually are, but… There’s always Benjaman Kyle and Michael Boatwright. How many cases could be the result of something like this?